In this 2009 photo provided by the New England Aquarium, a North Atlantic right whale swims with her calf in the Atlantic Ocean off the coast of the United States near the border between Florida and Georgia.
The Obama administration is opening the Eastern Seaboard to offshore oil exploration for the first time in decades.

Friday’s announcement is the first real step toward what could be a transformation in coastal states, creating thousands of jobs to support a new energy infrastructure. But it dismayed environmentalists and people who owe their livelihoods to fisheries and tourism.

The cannons create noise pollution in waters shared by whales, dolphins and turtles, sending sound waves many times louder than a jet engine reverberating through the deep every ten seconds for weeks at a time. Arguing that endangered species could be harmed was the environmental groups’ best hope for extending a decades-old ban against drilling off the U.S. Atlantic coast.

The U.S. Bureau of Ocean Energy Management acknowledged that thousands of sea creatures will be harmed even as it approved opening the outer continental shelf from Delaware to Florida to exploration. Energy companies need the data as they prepare to apply for drilling leases in 2018, when current congressional limits expire.

“The bureau’s decision reflects a carefully analyzed and balanced approach that will allow us to increase our understanding of potential offshore resources while protecting the human, marine, and coastal environments,” acting BOEM Director Walter Cruickshank said in a statement.

Sonic cannons are already used in the western Gulf of Mexico, off Alaska and in other offshore oil operations around the world. They are towed behind boats, sending down pulses of sound that reverberate beneath the sea floor and rebound to the surface. Hydrophones capture the results, which computers translate into high resolution, three-dimensional images.

“It’s like a sonogram of the Earth,” said Andy Radford, a petroleum engineer at the American Petroleum Institute, an oil and gas trade association in Washington DC. “You can’t see the oil and gas, but you can see the structures in the Earth that might hold oil and gas.”

The surveys also can map marine habitats and identify solid undersea flooring for wind energy turbines. But fossil fuel mostly funds this research, and corporations keep the data secret, disclosing it only to the government.

“They paid for it, so I can see why they don’t want to share. These things are not cheap,” said John Jaeger, a University of Florida geology professor.

Oil lobbyists say drilling for the estimated 4.72 billion barrels of recoverable oil and 37.51 trillion cubic feet of natural gas that lies beneath federal waters from Florida to Maine could generate $195 billion in investment and spending between 2017 and 2035, contributing $23.5 billion per year to the economy.

These estimates describe the total amount of energy “technically recoverable” from the nation’s outer continental shelf, but the Atlantic seabed from New Jersey through New England remains off limits for now. While some states have passed drilling bans, Virginia and the Carolinas asked for the surveys, bureau officials explained Friday.

“I honestly feel we can go offshore and harvest the energy that’s out there,” said South Carolina state Sen Paul Campbell. “I think we’re kind of foolish not to.”

In any case, the area to be mapped is farther offshore in federal waters, beyond the reach of state law.

The sonic cannons are often fired continually for weeks or months, and multiple mapping projects may operate simultaneously. To get permits, companies will need to have whale-spotting observers onboard and do undersea acoustic tests to avoid nearby species. Certain habitats will be closed during birthing or feeding seasons.

Still, underwater microphones have picked up blasts from these sonic cannons over distances of thousands of miles, and the constant banging — amplified in water by orders of magnitude — will be impossible for many species to avoid.

Whales and dolphins depend on being able to hear their own much less powerful echolocation to feed, communicate and keep in touch with their family groups across hundreds of miles. Even fish and crabs navigate and communicate by sound, said Grant Gilmore, an expert on fish ecology in Vero Beach, Fla.